/*
 * OREKIT-X
 * Copyright 2002-2008 CS Communication & Systemes
 * 
 * Parts of this software package have been licensed to CS
 * Communication & Systemes (CS) under one or more contributor license
 * agreements.  See the NOTICE file distributed with this work for
 * additional information.
 *  
 * This is an experimental copy of OREKIT from www.orekit.org.
 * Please use the original OREKIT from orekit.org for normal work
 * unrelated to this research project.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you
 * may not use this file except in compliance with the License.  You
 * may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied.  See the License for the specific language governing
 * permissions and limitations under the License.
 */
package ore.forces.drag;

import java.io.Serializable;

import ore.Frame;
import ore.errors.OrekitException;
import ore.time.AbsoluteDate;

import org.apache.commons.math.geometry.Vector3D;


/** 
 * Interface for atmospheric models.
 * 
 * @author Luc Maisonobe
 */
public interface Atmosphere
    extends java.io.Serializable
{

    /** 
     * @param date current date
     * @param position current position in frame
     * @param frame the frame in which is defined the position
     * 
     * @return Local density (kg/m<sup>3</sup>)
     * 
     * @exception OrekitException if date is out of range of solar activity model
     * or if some frame conversion cannot be performed
     */
    public double getDensity(AbsoluteDate date, Vector3D position, Frame frame)
        throws OrekitException;

    /** 
     * Get the inertial velocity of atmosphere molecules.
     * 
     * @param date current date
     * @param position current position in frame
     * @param frame the frame in which is defined the position
     * 
     * @return Velocity (m/s) (defined in the same frame as the position)
     * 
     * @exception OrekitException if some conversion cannot be performed
     */
    public Vector3D getVelocity(AbsoluteDate date, Vector3D position, Frame frame)
        throws OrekitException;

}
